438 research outputs found
Chinas grain production: a decade of consecutive growth or stagnation?
pre-printSome progressive writers have argued that while China's agricultural privatization achieved short-term gains, it did so by undermining longterm production facilities such as the infrastructure and public services built in the socialist era.1 Environmental scholars have questioned the sustainability of the Chinese agriculture. In a report published in 1995, Lester R. Brown raised the question: "Who will feed China?" He argued that the Chinese population's changing diet, shrinking cropland, stagnating productivity, and environmental constraints would lead to a widening gap between China's food supply and demand, a gap the world's leading grain exporters would not be able to fill.
Invariance Matters: Exemplar Memory for Domain Adaptive Person Re-identification
This paper considers the domain adaptive person re-identification (re-ID)
problem: learning a re-ID model from a labeled source domain and an unlabeled
target domain. Conventional methods are mainly to reduce feature distribution
gap between the source and target domains. However, these studies largely
neglect the intra-domain variations in the target domain, which contain
critical factors influencing the testing performance on the target domain. In
this work, we comprehensively investigate into the intra-domain variations of
the target domain and propose to generalize the re-ID model w.r.t three types
of the underlying invariance, i.e., exemplar-invariance, camera-invariance and
neighborhood-invariance. To achieve this goal, an exemplar memory is introduced
to store features of the target domain and accommodate the three invariance
properties. The memory allows us to enforce the invariance constraints over
global training batch without significantly increasing computation cost.
Experiment demonstrates that the three invariance properties and the proposed
memory are indispensable towards an effective domain adaptation system. Results
on three re-ID domains show that our domain adaptation accuracy outperforms the
state of the art by a large margin. Code is available at:
https://github.com/zhunzhong07/ECNComment: To appear in CVPR 201
Exploring Data Augmentations on Self-/Semi-/Fully- Supervised Pre-trained Models
Data augmentation has become a standard component of vision pre-trained
models to capture the invariance between augmented views. In practice,
augmentation techniques that mask regions of a sample with zero/mean values or
patches from other samples are commonly employed in pre-trained models with
self-/semi-/fully-supervised contrastive losses. However, the underlying
mechanism behind the effectiveness of these augmentation techniques remains
poorly explored. To investigate the problems, we conduct an empirical study to
quantify how data augmentation affects performance. Concretely, we apply 4
types of data augmentations termed with Random Erasing, CutOut, CutMix and
MixUp to a series of self-/semi-/fully- supervised pre-trained models. We
report their performance on vision tasks such as image classification, object
detection, instance segmentation, and semantic segmentation. We then explicitly
evaluate the invariance and diversity of the feature embedding. We observe
that: 1) Masking regions of the images decreases the invariance of the learned
feature embedding while providing a more considerable diversity. 2) Manual
annotations do not change the invariance or diversity of the learned feature
embedding. 3) The MixUp approach improves the diversity significantly, with
only a marginal decrease in terms of the invariance
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